|
| |
|
|
A185118
|
|
Number of connected 2-regular simple graphs on n vertices with girth at least 8.
|
|
12
|
|
|
|
1, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
|
OFFSET
|
0
|
|
|
COMMENTS
|
|
|
|
LINKS
|
|
|
|
FORMULA
|
a(0)=1; for 0 < n < 8 a(n)=0; for n >= 8, a(n)=1.
This sequence is the inverse Euler transformation of A185328.
|
|
|
EXAMPLE
|
The null graph is vacuously 2-regular and, being acyclic, has infinite girth.
There are no 2-regular simple graphs with 1 or 2 vertices.
The n-cycle has girth n.
|
|
|
CROSSREFS
|
2-regular simple graphs with girth at least 8: this sequence (connected), A185228 (disconnected), A185328 (not necessarily connected).
Connected k-regular simple graphs with girth at least 8: A186728 (any k), A186718 (triangle); specific k: this sequence (k=2), A014376 (k=3).
|
|
|
KEYWORD
|
nonn,easy
|
|
|
AUTHOR
|
|
|
|
STATUS
|
approved
|
| |
|
|
